The various types of magnetographic printers presently known from patents, publications and commercial efforts generally involve a common operational process based on the use of a magnetizable tape which is advanced successively through the several functional stations involved in visual image production. Initially, the tape is exposed to a magnetic image, typically rendered by a magnetic recording head responsively to digital data signals containing image information. Such magnetic image is latent and the tape is conveyed to a developing station where toner particles are applied to the tape. The tape is next advanced to a transfer station at which point the tape is stopped and the toner-developed latent image is transferred to a visual image recording medium, such as paper. The image upon the paper is of preliminary character following such transfer in that it is readily disturbed. Fusing apparatus receives the paper and renders the visual image permanent. The tape is advanced through a cleaning station in preparation for further cycles in which the foregoing steps are repeated.
As the tape is typically an elongate endless web, it is advanced lineally past the magnetic head and the characters of the image appear successively lengthwise along the tape. To transfer such information to paper so as to define a line of text, the paper need be moved in a direction transverse to the direction of movement of the tape. Thus, a paper path need be established from a paper supply and through the tape transport apparatus and then into apparatus for rendering permanent the transferred image, for example, a heat fusing station. Employment of a limited length paper travel path is desirable between the point of image transfer and the point of image fusion, as the preliminary image is tenuous.
Apart from the various design parameters, above noted, i.e., tape movement control, transverse paths for magnetic tape and paper and limited path length for paper movement, the magnetographic printer designer is faced with the further consideration that the environment in which the tape is used is relatively abrasive, involving the cyclic application to and removal from the sensitive tape of coarse toner particles. Accordingly, the tape should be readily replaceable. Further, there is need for maintaining the toner reservoir in such location that stray toner does not find its way to the tape or mechanism. From applicant's point of view, there has not been heretofore provided a satisfactory compromise among these several competing design demands, such that past known magnetographic printers have had less than desired commercial realization.